Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Chapter 7, Creating Volumes
Creating a Volume with Dirty Region Logging Enabled
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Creating a Volume with Dirty Region Logging Enabled
Note The procedure in this section is applicable to volumes that are created in disk
groups with a version number of less than 110. To enable DRL or sequential DRL on
a volume that is created within a disk group with a version number of 110 or
greater, follow the procedure described in “Creating a Volume with a Version 20
DCO Volume” on page 212, which creates the DRL logs within the plexes of a
version 20 DCO volume.
Dirty region logging (DRL), if enabled, speeds recovery of mirrored volumes after a
system crash. To enable DRL on a volume that is created within a disk group with a
version number between 20 and 100, specify the logtype=drl attribute to the
vxassist make command as shown in this example usage:
# vxassist [-g diskgroup] make volume length layout=layout \
logtype=drl [nlog=n] [loglen=size] [other attributes]
The nlog attribute can be used to specify the number of log plexes to add. By default, one
log plex is added. The loglen attribute specifies the size of the log, where each bit
represents one region in the volume. For example, the size of the log would need to be 20K
for a 10GB volume with a region size of 64 kilobytes.
For example, to create a mirrored 10GB volume, vol02, with two log plexes in the disk
group, mydg, use the following command:
# vxassist -g mydg make vol02 10g layout=mirror logtype=drl \
nlog=2 nmirror=2
Sequential DRL limits the number of dirty regions for volumes that are written to
sequentially, such as database replay logs. To enable sequential DRL on a volume that is
created within a disk group with a version number between 70 and 100, specify the
logtype=drlseq attribute to the vxassist make command.
# vxassist [-g diskgroup] make volume length layout=layout \
logtype=drlseq [nlog=n] [other attributes]
Note If you also want to allow the use of Persistent FastResync with the volume, use the
procedure described in “Cre a tin g a Volum e with a Ve rsi on 0 DCO Volum e” on
page 210.